/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 * <p>
 * http://www.apache.org/licenses/LICENSE-2.0
 * <p>
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.hadoop.hive.ql.exec;

import org.apache.hadoop.hive.ql.lib.Node;

import java.util.Collection;
import java.util.HashSet;
import java.util.Set;

/**
 * Simple node iterating utils
 */
public class NodeUtils {

    public static <T> void iterateTask(Collection<Task<?>> tasks, Class<T> clazz, Function<T> function) {
        Set<Task> visited = new HashSet<Task>();
        for(Task<?> task : tasks) {
            iterateTask(task, clazz, function, visited);
        }
        return;
    }

    private static <T> void iterateTask(Task<?> task, Class<T> clazz, Function<T> function, Set<Task> visited) {
        if(!visited.add(task)) {
            return;
        }
        if(clazz.isInstance(task)) {
            function.apply(clazz.cast(task));
        }
        // this is for ConditionalTask
        if(task.getDependentTasks() != null) {
            for(Task<?> dependent : task.getDependentTasks()) {
                iterateTask(dependent, clazz, function, visited);
            }
        }
    }

    public static <T> void iterate(Collection<? extends Node> nodes, Class<T> clazz, Function<T> function) {
        Set<Node> visited = new HashSet<Node>();
        for(Node task : nodes) {
            iterate(task, clazz, function, visited);
        }
        return;
    }

    private static <T> void iterate(Node node, Class<T> clazz, Function<T> function, Set<Node> visited) {
        if(!visited.add(node)) {
            return;
        }
        if(clazz.isInstance(node)) {
            function.apply(clazz.cast(node));
        }
        if(node.getChildren() != null) {
            for(Node child : node.getChildren()) {
                iterate(child, clazz, function, visited);
            }
        }
    }

    public static interface Function<T> {
        void apply(T argument);
    }
}
